This invention relates to a novel process for preparation of hexahydroindazolones. The production of such hexahydroindazolones has been known in the past. Typical of the processes utilized was one involving an intermediate whose preparation was taught by H. R. Snyder et al., Org. Syn. Coll. Vol. II, 531-534 (1943) wherein ethyl cyclohexanone-2-carboxylate was prepared in an organic solvent from cyclohexanone and diethyl oxalate. ##STR1## The ethyl cyclohexanone-2-carboxylate and aromatic hydrazines could then be reacted to form hexahydroindazolones. ##STR2## There are problems associated with such a reaction in that the keto ester is difficult to prepare and is not readily available in large quantities. Additionally, there are problems associated with the use of organic solvents. The Fe and glass catalyzed decarbonylation can be difficult to control and dangerous pressure increases may occur. For reasonable yields, the intermediate glyoxylic ester must be distilled and can decarbonylate during distillation if traces of metal are present. The use of organic solvent presents problems of increased use and disposal costs relative to water. It also requires the use of the free hydrazine base for solubility reasons; any time the free base is liberated there is the risk of decomposition through oxidation.
Since the 2-aryl-1,2,4,5,6,7-hexahydro-3H-indazol-3-ones are important intermediates for making herbicides, an efficient process for preparing the indazolones in high yield is needed.